Copolymers of .alpha.,.beta.-unsaturated dicarboxylic acid esters and .alpha.-olefins are useful as lubricant compositions or additives. Some recent examples of disclosures include U.S. Pat. No. 4,931,197 to H. Beck et al. and Canadian Patent No. 1,238,448 to Akzo N.V. Copolymers of this type which are butanol esters of .alpha.-olefin-dicarboxylic acid copolymers (average molecular weight of 1200-2500) are, moreover, commercially available under the trademark KETJENLUBE from Akzo Chemicals Inc. and Akzo Chemicals b.v.